FAQ | Frequently Asked Questions |
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Für diesen Inhalt steht leider keine Übersetzungen zur Verfügung. Originaltext wird angezeigt. This FAQ answers general questions concerning FDT Technology and the FDT Group.FDT General:
DTM:
Group:FDT General:What is FDT?FDT stands for Field Device Tool and is a technology for configuration and access of field devices. This technology is established as an open standard and therefore vendor independent. Device manufacturers add to their individual field devices a piece of software called Device Type Manager or DTM. FDT compliant software tools - so-called frame applications - can communicate via DTMs across fieldbuses with each device. Configuration of the device and access of the data is a child's play. With the aid of the frame applications, the information of processes in the field is accessible in realtime and is available across the life cycle of a plant or application. Those tools support you efficiently during engineering, installation, commissioning, production and maintenance. Which companies support FDT?Currently the FDT Group consists of these members. However, there are more companies that use FDT. How does FDT? workFDT standardizes the communication between field devices and tools used to engineer and automate plants or applications. This tools can be for example engineering tools, production management tools, maintenance tools, or asset optimization tools. Here's how it works.The device supplier develops a software driver called Device Type Manager (DTM) for each of its devices or group of devices. DTM’s can be - broadly speaking - compared with printer drivers that we use for our office PC. A DTM for a device class that does not have direct access to communication is named DeviceDTM. The DeviceDTM encapsulates all the device-specific data, functions and business rules. DTMs can reach from a simple graphical user interface for setting device parameters up to a highly sophisticated application that, for example, can perform complex calculations for diagnostics and maintenance purposes or can implement arbitrarily complex business logics for device calibration. One DeviceDTM must exist for every device. The device manufacturer provides the DeviceDTM. However, the driver contents is inaccessible to third parties and the manufacturer’s know-how is protected. A DTM which has direct access to the communications backbone that connects the device to a particular fieldbus is called a Communications DTM (CommDTM). The CommDTM encapsulates all communication specific aspects. The system (host) engineering environment has an FDT “Container”, that defines a set of interfaces between the hosting application (‘Frame Application’ in terms of FDT) and the ‘device drivers’ (DTM). Frame Applications can be device configuration tools, control system-engineering tools, operator consoles, or asset management tools. FDT initiates the DTM and generally interfaces the device to the system engineering and operation environment. Key benefits of FDT for end usersEnd users want to use a unique, standard interface that connects any automation system to any device, so that they have the freedom of choice to select the device fitting best the demands of their applications, regardless of supplier or communication protocol. They want this “open” interface to access all the wealth of information available in modern field devices, even for the most complex ones. The specialized applications should support the devices through their life cycle and enable engineering, operation, monitoring, calibration, diagnostics, maintenance and audit trails. The engineering and configuration information should be displayed on a standard graphic interface and the tool should be easy to learn and easy to use. And finally, whatever the solution, it should evolve with the state of the art in communication and information technology, so that the automation investment is protected well into the future. Key benefits of FDT for automation suppliersAutomation suppliers are faced with the high development costs due to the very diverse environments in host systems and field devices, which require customized interfaces for every combination. They would much rather invest their resources where they belong, in specialized, differentiated features that bring benefits to the end users, rather than in integration problems. FDT provides a standard interface for all compliant systems and devices. Additionally, it is the same for automation systems and for stand alone tools. DTM’s leverage the existing DD’s (Device Descriptions) and are unique for each device (i.e. they need to be built only once, regardless of the host system), thereby protecting the supplier’s investment. Finally, the technology itself allows for migration to future platform developments such as evolution from COM to .Net. What happens when the operating system in my plant is changed?FDT frame applications and DTMs are programs, which only need to be reinstalled in a new the new system environment, just as system software. (Office 97 still runs under Windows XP) Both, Device DTMs and Communication DTMs are not comparable to the device drivers of the operating system. Thus, there is no dependence on the hardware installed in a computer. Only the computer hardware responsible for communication with the field devices, e.g. PROFIBUS card, requires, under certain circumstances, new system drivers. New DTMs are not required. Communication DTMs use system drivers, but are not concerned itself, comparable to OPC communication drivers. There will be still access to all data bases and device configurations. The storage of data and device configurations is done in FDT Frame Application. What happens if Microsoft withdraws a technology, e.g. COM, which is used by the plant system?Hardware, software and device technology build a single unit in a plant. If nothing is changed, nothing happens. In further developments of an operating system, an existing technology is mostly not (weiter-) developed anymore, but is still supported by the operating system. Up to now Microsoft has never dropped the history and has always provided an upward compatibility. DOS-Software is still running up to now in the DOS-Box, if it is engineered “clean” on BIOS (Basic Input/output System) interfaces. DOS-Software which works with BIOS interrupt-calls are able to access file formats, which even have not been known at time of development. Norton Commander is able to access NTFS file format. WORD 3.0 documents can still be opened in Windows XP. Microsoft has mostly pursued a migration strategy. A migration strategy has been provided for e.g. document formats (Word) or file formats (FAT32/NTFS). Conversion programs are available for the transformation. Microsoft has always created upward compatibility for internal interface technologies (e.g. DDE, OLE, COM). How are the functional relationships between operating system, control system, frame application and DTMs documented and certified?DTM certification is a prerequisite for all compatibility requirements regarding FDT technology. The certificate gives user the assurance that the DTM conforms strictly to the FDT standard. A certificate is issued only when the DTM has successfully passed the tests made with the dtmINSPECTOR. This is a software tool for all types of DTM. It logs both the behaviour of the DTM and any deviations in functionality. The FDT Group issues a certificate only when the DTM has passed the test without error. A similar certification process has been put in place for frame applications. The frame application may be an independent Windows program, or be integrated into a control or asset management system. It must be installed in this way in the operating system and is subject to the Windows criteria. How can you ensure a uniform user interface and operating philosopy for field devices?The Project Group “Style Guide” within the FDT Group is working on a standard for a uniform user interface and operating philosophy. The requirements have been formulated by end users (e.g. NAMUR AK 2.6 Fieldbus). These form the basis of the FDT Style Guide. The Style Guide includes a multilingual glossar. The Style Guide becomes part of DTM certification topDTM:How can I get a DTM for my field device?The device supplier develops the Device Type Manager (DTM) for each of its devices or group of devices and supplies it with the instrument. As a manufacturer of field devices I want to develop DTMs. What is your advice?
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